The author of the Dear Jane book is DIRECTLY copying the designs of the original book.
And Jane Stickney probably copied some of her designs from some she'd seen elsewhere.
The original Jane has been long dead, Even though the author is giving Jane full credit for the designs - where is the line between homage and plagiarism?
I just think most of the geometric designs have been around for so long, that it is hard to know the "true" source (I happen to think it's the Creator, but that's another line of thought)